Influence of Alkyl Chain on a Neutral-Carrier for Use in Selective Membranes Mercury Ions

The recognition element or ionophore of the ISEs, is the main constituent to be considered during their building, which is the reason to synthesize four molecules of the same family, all of them candidates to be the best recognition element for building a novel Hg(II) ions selective electrode with a solid inner contact. The difference between the four structures is the alkyl group bound to one of the sulphur donating groups, the aliphatic chain can be: methyl, ethyl, propyl or butyl. The electrodes were prepared for each of the ionophores synthesized using the composition of the ionophore membrane: o-NPOE:PVC:NaTPB with 5:62:33:1.0mg (%, w/w). The best neutral-carrier for the selective determination of mercury ions proved to be the ionophore containing the methyl in its structure, as demonstrated by its detection limit (9.1 ± 0.8) x 10⁻¹⁰ mol L^-1, linear range (1.0 x 10⁻⁹ to 1.0 x 10⁻¹) mol L^-1 and a Nernstian response (29.8 ± 0.4) mV decade^-1.